A beamforming microphone array (BMA) substantially improves the audio quality in a conferencing apparatus and application. Furthermore, a conferencing solution with a BMA needs to incorporate an acoustic echo canceller (AEC) for full duplex audio. Two strategies, “AEC first” and “beamformer first”, have been proposed to combine an acoustic echo canceller with a beamforming microphone array. The “beamformer first” method performs beamforming on microphone signals and subsequently echo cancellation is applied on the beamformed signals.
The “beamformer first” method is known to be computationally friendly but requires continuous learning in the echo canceller due to changing characteristics of the beamformer in response to changing acoustic scenarios such as talkers and noise. Often this renders the “beamformer first” method impractical for good conferencing systems. On the other hand, the “echo canceller first” system applies echo cancellation on each microphone signal and subsequently beamforming is applied on the echo cancelled signals.
The “AEC first” system provides better echo cancellation performance but is computationally intensive as the echo cancellation is applied for every microphone in the microphone array. The computational complexity increases as the number of microphones in the microphone array increases. This computational complexity increase results in a corresponding cost increase that places a practical limit on the number of microphones that can be used in a microphone array, which, in turn, limits the maximum benefit that can be obtained from the beamforming algorithm.
The present disclosure implements a conferencing solution with a BMA and AEC in the “beamformer first” configuration with fixed beams followed by echo cancellers for each beam. This solution enables an increase in microphones for a better beamforming without the need for additional echo cancellers as the number of microphones increases. In addition, the present disclosure provides that the echo cancellers do not need to adapt all the time as a result of large changes in the beamformer because the number of beams and beam pickup patterns are fixed. Therefore, the present disclosure provides good echo cancellation performance without a huge increase in computational complexity for a large number of microphones.